Wireless Intelligent Network (WIN) Support for Centralized Service Control in an IP Multimedia Subsystem (IMS) Network

ABSTRACT

Feature control signaling can be transported from a handset to a network-based service platform when the handset is active on an existing call, using three-way calling and Intelligent Network (IN) capabilities to pass feature control information from the user device to a network-based service platform. Although Wireless Intelligent Network (WIN) standards do not support mid-call triggers, handset emulation of three-way-calling (3WC) behavior allows a handset to send a digit string (representing a particular feature-related event) to a network-based service platform (in the context of a pseudo-3WC). Mid-call communications can be accomplished in this manner, allowing a network-based service platform to interpret and take action based on the received digit string, prior to releasing the additional call leg associated with the pseudo-3WC attempt. WIN mechanisms can also be used to send feature control signals from a network-based service platform to a handset. These mechanisms can be used to promote consistent service offerings for users who are served by networks that are comprised of different technologies. These mechanisms can also be used to help operators transition their networks to support emerging network technologies.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 60/781,785, filed Mar. 13, 2006, which is herebyincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to the field oftelecommunications networks and the provisioning and implementation ofservices in such networks. More particularly, the invention relates towireless telecommunications networks and IP Multimedia Subsystems (IMS)networks, and the use of Wireless Intelligent Network (WIN)functionality to support an IMS-based centralized service executionmodel.

BACKGROUND OF THE INVENTION

Wireless standards (Third Generation Partnership Program [3GPP] and3GPP2 Voice Call Continuity [VCC]) are exploring mechanisms to allow VCCusers to move between Circuit-Switched (CS) access (via cellularsystems) and other wireless access (e.g., WiFi/Wireless LAN access intoan IMS infrastructure).

It is important that the corresponding “domain transfer” mechanism,applied when an existing call is in progress in one domain, should allowthe transfer of the existing bearer path to the alternate domain. Thedomain transfer mechanism should also support the transfer of asignaling path in the new domain. In addition, the user should ideallyexperience seamless mobility during and after the domain transfer.

To address service mobility, the industry has pursued two basicapproaches—a distributed service execution model and an (IMS-based)centralized service execution model. FIG. 1 depicts the basicarchitecture of these two service models.

In the CS cellular model 100, voice services are typically offered viathe Mobile Switching Center (MSC) 102. Such features can be MSC-basedfeatures 104, whereby the service logic resides in the MSC, and the MSCretrieves user profile information 106 from the Home Location Register(HLR) 108 to determine whether a selected feature is subscribed for andis active for a particular user. Alternatively, Intelligent Network (IN)based services 110 can be invoked, using triggers that are armed in theMSC—this mechanism causes the MSC to request instructions from a ServiceControl Point (SCP) 112, which executes IN service logic 110 thatdefines the particular service behavior.

In the IMS model 120, similar functionality is provided via a differentmechanism. With IMS, the service logic 122 resides in an ApplicationServer 124. The Home Subscriber Server (HSS) 126 stores user-relatedprofile information 128, including initial Filter Criteria (iFC) thatare used to trigger special service processing. This iFC mechanism isused to arm triggers 130 at a (Serving) Call Session Control Function(CSCF) 132. When a particular iFC condition is satisfied, the CSCF willcommunicate with a corresponding Application Server (as designated bythe iFC), which will invoke the desired service behavior.

In general, the distributed service execution model attempts to offerservices via the network where the user is currently attached. Thus, theuser might access MSC-based or IN-based services when accessing the CSdomain—but might access IMS-based services when accessing the IMSdomain.

In contrast, the (IMS-based) centralized service execution modelattempts to offer IMS-based services to the user, independent of thenetwork where the user is currently attached (i.e., even when the useris accessing the CS domain). This model promotes consistent execution ofIMS-based services, independent of the user's current access. This modelmakes more limited use of the CS service infrastructure (as required toenable IMS service execution).

The centralized service execution model offers a number of advantagesover the distributed service execution model. For example, it provides amechanism to allow the user's features to operate consistently,independent of the user's current access. The centralized serviceexecution model also allows the user's features to be created in acommon (IMS-based) manner—thereby avoiding the need to create and deploymultiple versions of the same services (for cellular and IMS domains).The model focuses the feature-interaction problem on a single (IMS)domain, eliminating the need to address interactions between servicesthat might otherwise execute in different domains (e.g., as MSC-basedfeatures, IN-based features, or IMS-based features). The centralizedservice execution model is more forward-looking, consistent with theintended direction of some operators who desire to move toward anIMS-based network infrastructure. The model provides a framework foraddressing some difficulties that might otherwise persist with thedistributed service execution model. For example, if a user invokes anMSC-based multi-leg call feature, and then moves to the IMS domain, itmay be difficult to transfer the current CS connection and call-stateinformation to the IMS domain.

This problem is illustrated in FIG. 2. In FIG. 2, if a user handset 200invokes an MSC-based multi-leg call feature 202, and subsequently wishesto transfer that connection and call-state information to the IMSdomain, this might require the multiple bearer connections to becorrelated and established in the IMS domain, in order to re-constructthe current call state in the IMS domain. This can require complexprocessing—and would be further complicated if one of the existing CScall legs 204, 206 happened to be on hold at the time of the domaintransfer.

With the centralized service execution model, the MSC 300 would insteadmaintain a single bearer channel to the IMS domain (e.g., relying on aMedia Resource Function (MRF) 302 within the IMS domain to provide anybridging/media-manipulation functionality). This is illustrated in FIG.3.

FIG. 3 illustrates the need for a mechanism to exchange feature control304 signaling between the user device 306 and an IMS-based ApplicationServer 308. This mechanism should support bi-directional operation andshould be enabled during an active CS call, allowing the network to sendnotifications to the user (e.g., notification of incoming call, as usedin conjunction with call waiting) and allowing the user to send featurecontrol information to the Application Server (e.g., “hold”, “join”,“request for pre-paid balance”, etc.)

Whereas existing mechanisms support the ability to exchange featurecontrol messages when the user is served by the IMS domain (i.e., basedon use of the Session Initiation Protocol (SIP)), there is a need for amechanism that can be used to support such feature control signalingwhen the user is served by the CS domain as illustrated in FIG. 3.

For GSM networks, the use of Unstructured Supplementary Services Data(USSD) capability has been defined for this purpose—allowing a GSMhandset to communicate with a network-based service platform. It isnoted that this solution is not yet fully defined. Message formats forservice requests need to be identified. Some options include the use ofSIP templates or feature codes.

For CDMA network deployments, no USSD-like mechanism is currentlyavailable. However, the industry is currently exploring at least twooptions for this: (i) support for simultaneous packet and circuitservice—where the packet capability might be used to enablecommunications between the user device and a network-based serviceplatform during an active CS call; and, (ii) support for a modifiedShort Message Service (SMS) capability—allowing the user device tosignal via the CS access network, which would then relay such messagingto a network-based service platform.

Currently, the USSD solution is only defined for GSM networks. Thus,there remains a need for a solution specifically targeted at CDMAnetworks, where USSD is not available. Other potential solutions forCDMA networks would require network modifications—making them morecostly and potentially delaying the deployment of this capability.

BRIEF SUMMARY OF THE INVENTION

The invention enables feature control signaling between the user handsetand a network-based service platform (when the user handset is served byCS access) based on the use of Wireless Intelligent Network (WIN)technology.

In the present invention, WIN mechanisms are used to support theexchange of feature control signals between a handset and anetwork-based service platform. As used herein, the term “network-basedservice platform” refers to a network component (which can be composedof a single element or a distributed group of elements) that supportsthe execution of service logic that is used to offer communicationsservices. The network-based service platform is capable of executingservice logic that spans across multiple technology domains, includingthe ability to communicate via intelligent network (IN) technology.Examples of such a network-based service platform include, but are notlimited to, a network component (which can comprise a single element ora distributed group of elements) that supports any of the following: thecombined functionality of a Wireless Intelligent Network (WIN) ServiceControl Point (SCP) and an IMS Application Server (AS); the combinedfunctionality of a Customized Application Mobile Enhanced Logic (CAMEL)Service Control Function (SCF) and an IMS AS; the combined functionalityof an Advanced Intelligent Network (AIN) Service Control Point (SCP) andan IMS AS; and the combined functionality of a Core INAP Service ControlFunction (SCF) and an IMS AS.

The proposed solution can be broken down into two separable mechanisms.The first mechanism addresses how to allow the user handset to sendfeature control information to a network-based service platform (e.g.,“hold”, “join”, etc.). The present invention makes use of an appropriateoriginating WIN trigger (e.g., All_Calls) that is armed at the visitedMSC when the user handset registers with that MSC. Although WINstandards do not support mid-call triggers, handset emulation ofthree-way-calling (3WC) behavior allows a digit string (generated by thehandset in the context of a pseudo-3WC) to be sent to a network-basedservice platform. Mid-call communications can be accomplished in thismanner, allowing the network-based service platform to interpret andtake action based on the received digit string, prior to releasing theadditional call leg associated with the pseudo-3WC attempt.

The second mechanism addresses how to allow the network to sendnotifications to the user handset (e.g., notification of an incomingcall, as used in conjunction with call waiting).

By combining the two mechanisms that are illustrated in FIGS. 4 and 5,standard WIN-based capabilities can be applied to enable feature controlsignaling between the user handset and a network-based service platform(when the user is served via CS access).

The result of combining the mechanisms is a system that does not requireany new capabilities in existing cellular Radio Access Networks or inexisting MSCs (or in existing HLRs, as with the USSD approach). Itrelies solely on existing (i.e., already standardized) WIN capabilitiesfrom the current cellular networks, thereby avoiding the need foradditional network enhancements.

The following detailed description focuses on the use of WIN to supportthe desired capabilities. CDMA networks are viewed as a principalapplication for this capability. However, it is noted that analogoussolutions are possible for other IN-based network technologies, otherthan WIN (e.g., corresponding Customized Application Mobile EnhancedLogic (CAMEL)-based procedures might be pursued if USSD capabilities arenot available, or if a more common approach is desired across GSM andCDMA solutions). A similar approach might also be pursued for wirelinenetworks, potentially helping to facilitate the migration path forexisting wireline network operators as they evolve their networkstowards an IMS-based approach.

The present invention will be more clearly understood when the followingdetailed description is read in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the architecture of the CS cellular and IMS serviceexecution models.

FIG. 2 shows multi-leg treatment of a session within a distributedservice execution model.

FIG. 3 shows multi-leg treatment of a session within a centralizedservice execution model.

FIG. 4 shows the mechanism to support feature control signaling from auser to a network-based service platform (with feedback in the reversedirection).

FIG. 5 shows the mechanism for using standard WIN Call Control Directive(CCDIR) messages to request the MSC to take particular feature-relatedactions during an existing call.

FIG. 6 shows a signal flow associated with a Call Waiting application.

FIG. 7 shows a signal flow associated with a Three Way Callingapplication.

DETAILED DESCRIPTION

The proposed approach to enable feature control signaling between a userhandset and a network-based service platform (when the user handset isserved by CS access) is based on the use of Wireless Intelligent Network(WIN) technology. Current WIN standards do not include support for anymid-call triggers. Thus, a ‘conventional’ IN approach for supporting thedelivery of mid-call feature-related signaling from the handset to anetwork-based service platform is not available. Also, the continuedexpansion of WIN capabilities on existing MSCs is not generally favored,given the current emphasis on more forward-looking IMS technologies fordeployment of advanced services, so the addition of mid-call triggers infuture WIN standards is unlikely to be pursued. The present inventionprovides a mechanism for supporting such mid-call feature-relatedsignaling.

The solution is broken down into two separable mechanisms. The firstmechanism addresses how to allow the user to send feature controlinformation to a network-based service platform (e.g., “hold”, “join”,etc.). This proposed mechanism is illustrated in FIG. 4. The proposedapproach makes use of existing WIN call origination triggers. Any onefrom a number of existing originating WIN triggers can be used, such asthe All_Calls, Double_Introducing_Star, Single_Introducing_Star,Double_Introducing_Pound, Single_Introducing_Pound, K_Digit, orOrigination_Attempt_Authorized triggers. The specific trigger type to bechosen may depend on the specific format of the feature code digits tobe delivered, as well as whether particular triggers are to be appliedby the network operator for other purposes—yet this decision does notimpact the general mechanism proposed here. The present invention usesan appropriate originating WIN trigger (e.g., All_Calls) that is armedat the visited MSC (using standard cellular procedures, when the userhandset registers with that MSC). In addition, the present inventionrequires that (the CallingFeaturesIndicator item within) the userprofile (normally obtained from the HLR during registration) shouldindicate that the user is subscribed to the three-way calling (3WC)feature. This differs from the normal rule for the IMS centralizedservice execution model, which would suggest that MSC-based featuresshould be disabled, in favor of execution of corresponding IMS-basedservices.

By arming the above WIN trigger and enabling the MSC-based 3WC feature,it is noted that virtually all originating call requests (excludingemergency calls, but including requests to establish an additional callleg for a three-way call) will result in the corresponding WIN triggercondition being satisfied at the MSC. Thus, whenever the handset isactive on a CS call and subsequently initiates an additional call (as instep 1 of FIG. 4), the MSC will send a WIN OriginationRequest (ORREQ)message that is directed to a network-based service platform (i.e., SCP,as specified for the corresponding trigger). The ORREQ message (step 2)will include the digits that were received from the user handset, alongwith other information such as the Mobile Station Identifier (MSID) andthe specific type of trigger that was detected. At this point, the SCPwill interpret the digits received in the ORREQ message to determine theintended service request and (behaving as an Application Server in theIMS domain) will invoke the necessary processing for the desiredservice. The SCP then responds back to the MSC (step 3) to instruct theMSC to abort further processing associated with this “3WC” (feature)request—and may also optionally request that an indication be providedto the user (e.g., via the inclusion of the DisplayText and/orAnnouncementList parameters). To instruct the MSC to drop this new callleg (associated with the 3WC attempt) and still retain the existingcall, the SCP can populate the appropriate AccessDeniedReason parameter(e.g., with a value of “Service denied”) or ActionCode parameter (e.g.,with a value of “Disconnect Call Leg”). Depending upon MSC support forsuch treatment, the SCP can alternately return a special Digits(dialed)or TerminationList value, to cause the MSC to route the additional callleg into the IMS network (from where appropriate IMS feature/leg-releaseprocessing could be provided).

The second mechanism addresses how to allow the network to sendnotifications to the user (e.g., notification of incoming call, as usedin conjunction with call waiting). This mechanism is illustrated in FIG.5. FIG. 5 illustrates how the standard WIN Call Control Directive(CCDIR) message can be used to request the MSC to take particularfeature-related actions during an existing call. Note that this mid-callmechanism already exists in the WIN standards (e.g., used to supportPre-Paid Charging)—yet is not considered a mid-call trigger, sincetrigger conditions are detected and acted upon by the MSC, whereas thismessage originates from the SCP.

To support the delivery of feature-related information from the networkto the handset, the SCP will send a WIN CCDIR message (step 1) that isdirected to the MSC. The DisplayText parameter enables the delivery of atextual message to the user (e.g., a notification of an additionalincoming call, to allow the user to invoke call waiting—via themechanism outlined previously in FIG. 4). The BillingID parameteridentifies the specific existing call (to which this message isassociated), and the ActionCode and/or AnnouncementList parameters areused to designate any desired feature-related actions (e.g., calltear-down, or playing of an announcement/tone). The MSC performs therequested actions (e.g., delivering text to be displayed via thehandset, as depicted in step 2) and responds back to the SCP (asillustrated in step 3).

By combining the mechanisms that are illustrated in FIGS. 4 and 5, theresult is a novel approach for how standard WIN-based capabilities canbe applied to enable feature control signaling between the user handsetand a network-based service platform (when the user handset is servedvia CS access). The present invention has the following properties.First, the invention requires new logic that must be incorporated intothe applicable dual-mode handsets. Such handsets must be able tointerpret user inputs (via appropriate function keys or otherhandset-specific user interface technologies) in order to determineassociated digit strings for each feature control event. These digitstrings may be sent as ‘feature codes’ in the context of “pseudo-3WC”invocations.

Second, the invention does not require any new capabilities in existingcellular Radio Access Networks or in existing MSCs (or in existing HLRs,as with the USSD approach). It relies solely on existing (i.e., alreadystandardized) WIN capabilities from the current cellular networks,thereby avoiding the need for additional network enhancements.

This present invention focuses on the use of WIN to support the desiredcapabilities. CDMA networks are viewed as the principal market for thiscapability (given the lack of other suitable solutions for addressingthis market need). However, it is noted that analogous solutions mightbe pursued for other IN-based network technologies, other than WIN(e.g., corresponding CAMEL-based procedures might be pursued if USSDcapabilities are not available, or if a more common approach is desiredacross GSM and CDMA solutions). A similar approach might also be pursuedfor wireline networks, potentially helping to facilitate the migrationpath for existing wireline network operators as they evolve theirnetworks towards an IMS-based approach. Thus, this concept can beapplied to the following areas: (i) use of WIN to support an IMScentralized service control model (as described herein); (ii) use ofCustomized Application Mobile Enhanced Logic (CAMEL) to support an IMScentralized service control model; (iii) use of wireline IN-basedtechnologies such as Advanced Intelligent Networks (AIN) to support anIMS centralized service control model; and, (iv) use of wirelineIN-based technologies such as Core INAP to support an IMS centralizedservice control model.

Usage of Invention for Several Illustrative Services

Having described the invention in general terms, the followingdescription illustrates how this invention could be applied to severalspecific services (i.e., for Call Waiting [CW] and for Three-Way Calling[3WC]).

The overall processing associated with a Call Waiting invocation ispartitioned into five segments, as highlighted in FIG. 6 and brieflydiscussed below.

1. When an incoming call arrives for a CW subscriber with an existingactive CS call, the CW Application Server (AS) sends a WIN CCDIR messageto the MSC. The DisplayText parameter is used to deliver a textualmessage to the CW subscriber (i.e., a notification of an additionalincoming call, including the calling party identity), used as a CWnotification. The BillingiD parameter identifies the specific existingcall to which the message is associated. The MSC performs the requestedactions, i.e., delivering text to be displayed via the handset, andresponds back to the CW AS.

2. Upon receiving the incoming call notification, the CW subscriberdecides to invoke CW, e.g., via a flash signal. The handset detects thisevent and generates a Flash with Information message, containing aspecial digit string that is used to designate the user-requested event.The MSC receives this message and detects that a corresponding WINtrigger, e.g., All_Calls, is armed. The MSC then sends an ORREQ messageto the designated SCP (i.e., to the CW AS depicted in FIG. 6),containing the corresponding feature control digits. The CW AS uses thereceived digits to determine the appropriate (CW) logic to invoke. Inthis case, the CW AS responds with an orreq message that instructs theMSC to abort its processing, while leaving the existing call intact.

3. The CW AS initiates procedures to establish a connection from the newincoming caller to the target CW subscriber (e.g., using Third-PartyCall Control [3PCC] logic in the IMS domain). The CW AS also places theprior connection (between the CW subscriber and the original connectedparty) on hold (e.g., via re-INVITE procedures in the IMS domain).

Based on the above processing, the CW subscriber is connected to the newincoming call and the original call is placed on hold.

Further processing (associated with subsequent CW logic) is partitionedinto the final two segments, as depicted in FIG. 6.

4. The CW subscriber can toggle between the set of active and held callsvia flash signals. The handset detects this event and generates a Flashwith Information message, containing a special digit string that is usedto designate the user-requested event. The MSC receives this message anddetects that a corresponding WIN trigger (e.g., All_Calls) is armed. TheMSC sends an ORREQ message to the designated SCP (i.e., to the CW AS),containing the corresponding feature control digits. The CW AS uses thereceived digits to determine the appropriate (CW) logic to invoke. TheCW AS responds with an orreq message that instructs the MSC to abort itsprocessing, while leaving the existing call intact.

5. The CW AS initiates procedures to re-establish the original call tothe target CW subscriber and to place the connection between the CWsubscriber and the new incoming call on hold (e.g., using re-INVITEprocedures in the IMS domain).

Based on the above processing, the CW logic is able to toggle theactive/held states of the connections between the CW subscriber and thenew/original calls.

FIG. 7 illustrates how the current invention may be applied for ThreeWay Calling (3WC). In this flow, a Media Resource Function (MRF) is usedto provide the network-based bridging functionality for this service.

The overall processing (associated with the 3WC invocation) ispartitioned into four segments, as shown in FIG. 7 and described below.

1. The 3WC subscriber establishes an active call with another party(“Party 1”). Once this call is established, the 3WC subscriber decidesto invoke 3WC (e.g., via entry of address digits for the additionalparty [“Party 2”]). The handset detects this event and generates a Flashwith Information message, containing a digit string that includes theaddress of Party 2. The MSC receives this message and detects that acorresponding WIN trigger (e.g., All_Calls) is armed. The MSC thereforesends an ORREQ message to the designated SCP (i.e., to the 3WC AS shownin the figure), containing the corresponding digits. The 3WC AS uses thereceived digits to determine the appropriate (3WC) logic to invoke. Inthis case, the 3WC AS responds with an orreq message that instructs theMSC to abort its processing, while leaving the existing call intact.

2. The 3WC AS initiates procedures to establish a connection from the3WC subscriber to a Media Resource Function (MRF), e.g., using 3PCClogic in the IMS domain. The 3WC AS instructs the MRF to [a] establish aconnection from the 3WC subscriber toward the target party (Party 2) and[b] place the existing connection from the 3WC subscriber toward theoriginal connected party on hold (e.g., via 3PCC and re-INVITEprocedures in the IMS domain).

Based on the above processing, the 3WC subscriber is connected (via theMRF) to Party 2, and the original call leg toward Party 1 is placed onhold.

Subsequent processing associated with the 3WC service, used to bridgethe three parties together, is partitioned into two additional segmentsas briefly discussed below.

3. The 3WC subscriber requests to be bridged together with Parties 1 and2. The handset detects this event and generates a Flash with Informationmessage, containing a special digit string that is used to designate theuser-requested event. The MSC receives this message and detects that acorresponding WIN trigger (e.g., All_Calls) is armed. The MSC then sendsan ORREQ message to the designated SCP (i.e., to the 3WC AS), containingthe corresponding feature control digits. The 3WC AS responds with anorreq message that instructs the MSC to abort its processing, whileleaving the existing call intact.

4. The received digits are used to determine the appropriate (3WC) logicto invoke. The 3WC AS initiates procedures to bridge together the threecall legs (to the 3WC subscriber, to Party 1, and to Party 2) via theMRF to establish the three-way call (e.g., via 3PCC and re-INVITEprocedures in the IMS domain).

While there has been described and illustrated a method and system forsupporting feature control signaling between a user handset and anetwork-based service platform when the user handset is served bycircuit switched access based on the use of WIN triggers, it will beapparent to those skilled in the art that modifications and variationsare possible without deviating from the spirit and broad scope of thepresent invention which shall be limited solely by the scope of theclaims appended hereto.

1. A method of using a first handset having an existing establishedcommunication session with a second handset, the method comprising:detecting in the first handset a feature-event to be reported to anetwork-based service platform; selecting in the first handset a set offeature information to be sent in response to detecting thefeature-event; sending the feature information from the first handset toa network in response to detecting the feature-event to triggercommunication with the network-based service platform for invokingintended feature actions; re-establishing the communication session withthe second handset.
 2. The method of claim 1 further comprisingreceiving a message from the network-based service platform via thenetwork including feature information.
 3. The method of claim 1 furthercomprising: establishing a connection from the first handset to anetwork-based service platform to establish a multi-party session amongthe first handset, the second handset, and the network-based serviceplatform; removing the network-based service platform from theestablished session, in response to completion of network-based serviceplatform involvement.
 4. The method of claim 1, wherein the selecting inthe first handset is based at least in part on predefinedfeature-control digit strings maintained in the first handset.
 5. Themethod of claim 1, further comprising the first handset sending a Flashwith Information message to the network to invoke a pseudo-three-waycall.
 6. A communication device handset configured to use anetwork-based service platform for executing services on behalf of thehandset having an existing established communication session with asecond handset, the handset comprising: a processing device configuredto cause the handset to: detect a feature-event to be reported to anetwork-based service platform; select a set of feature information tobe sent in response to detecting the feature-event; send a messagecontaining the feature information to a network in response to detectingthe feature-event for invoking intended feature actions; re-establishthe communication session with the second handset; receive a messagefrom the network-based service platform via the network includingfeature information.
 7. The handset of claim 6 wherein the processingdevice is further configured to cause the handset to re-establish thecommunication session with the second handset.
 8. A method of using anetwork-based service platform for executing services on behalf of afirst handset having an existing established communication session witha second handset, the method comprising: interpreting featureinformation from the first handset to determine intended featureactions; invoking the intended feature actions via service logicexecution at a network-based service platform; instructing the networkto pass feature information to the first handset by sending a message tothe network-based service platform; and re-establishing a communicationssession between the first handset and the second handset.
 9. The methodof claim 8, wherein the detecting that a trigger condition has beensatisfied in the network is based on an Intelligent Network (IN) triggerthat is detected at a switching system in the network.
 10. The method ofclaim 9, wherein the trigger is based on a Wireless Intelligent Network(WIN) trigger that is detected at a Mobile Switching Center (MSC) in thenetwork.
 11. The method of claim 10, wherein the message comprisesfeature information and the sending the message to the network-basedservice platform is based on the IN trigger.
 12. The method of claim 11,wherein the message comprises a WIN OriginationRequest (ORREQ) messagethat is sent from the MSC to the network-based service platform.
 13. Themethod of claim 11, wherein the feature information contains afeature-control digit string is populated in a Digits(Dialed) parameterof an associated WIN message.
 14. The method of claim 8, wherein theinterpreting the feature information is based on the predefinedfeature-control digit strings.
 15. The method of claim 8, wherein theinvoking the intended feature actions via service logic execution at thenetwork-based service platform is based on centralized service controlin an IMS-based network.
 16. The method of claim 8, wherein theinstructing the network to pass feature information to the first handsetis based on sending a response from the network-based service platformto the switching system via the corresponding response to the INtrigger.
 17. The method of claim 16, wherein the response from thenetwork-based service platform to an MSC is a WIN OriginationRequest(ORREQ) response message.
 18. The method of claim 17, wherein the WINORREQ response message from the network-based service platform containsan AnnouncementList and/or DisplayText parameter for instructing the MSCto provide audible and/or visual indications to the first handset and/ora routing address for invoking processing elsewhere in the network. 19.The method of claim 16, wherein the re-establishing a communicationssession between the first handset and the second handset is based oninstructions from the network-based service platform that are conveyedto the switching system via parameters of the response from thenetwork-based service platform.
 20. The method of claim 19, wherein theresponse from the network-based service platform contains anAccessDeniedReason or ActionCode parameter populated to release apseudo-3WC call leg and reconnect the first handset and the secondhandset.
 21. The method of claim 8 further comprising: receiving thefeature information from the first handset; detecting that a triggercondition has been satisfied in the network, in response to receivingthe feature information from the first handset; determining in thenetwork the identification of a network-based service platform, inresponse to the detecting that the trigger condition has been satisfied;sending feature information from the network to the network-basedservice platform, in response to detecting that the trigger conditionhas been satisfied.
 22. A network apparatus having a network-basedservice platform for executing services on behalf of a first handsethaving an existing established communication session with a secondhandset, the network apparatus comprising: means for receiving a messagecontaining feature information from the first handset; means fordetecting that a trigger condition has been satisfied in response toreceiving the message containing the feature information is receivedfrom the first handset; means for determining the identification of anetwork-based service platform in response to the detecting that thetrigger condition has been satisfied; means for sending a messagecontaining feature information to the network-based service platform inresponse to the detecting that the trigger condition has been satisfied;means for interpreting the feature information contained in the messagethat is received by the network-based service platform to determineintended feature actions; means for invoking the intended featureactions via service logic execution at the network-based serviceplatform; means for passing feature information to the first handset bysending a message from the network-based service platform.
 23. A networkapparatus having a network-based service platform for executing serviceson behalf of a first handset having an existing establishedcommunication session with a second handset, the network apparatuscomprising: a network-based element configured to receive a messagecontaining feature information from the first handset, to detect that atrigger condition has been satisfied, and to send a message containingfeature information to a network-based service platform in response tothe detecting that the trigger condition has been satisfied; and acentralized service control element in the network-based serviceplatform configured to interpret the feature information contained inthe message received by the network-based service platform to determineintended feature actions, to invoke the intended feature actions viaservice logic execution and to send a message including featureinformation to the network-based element; wherein the network-basedelement is further configured to pass the feature information to thefirst handset.
 24. A network apparatus having a network-based serviceplatform for executing services on behalf of a first handset having anexisting established communication session with a second handset, thenetwork apparatus comprising: a centralized service control element inthe network-based service platform, the centralized service controlelement configured to detect an event and to determine that afeature-event needs to be reported to the first handset based on theevent; and a network-based element configured to receive a messagecontaining feature information from the centralized service controlelement and to send a handset message containing feature information tothe first handset; wherein the centralized service control element isfurther configured to invoke intended feature actions based upon thefeature information contained in the message that is sent to thenetwork-based element.